The present invention relates to an assembly of free wheels in tandem, including at least two free wheels with jamming cams and bearings associated with the free wheels, all of the jamming cams and bearings being housed between external and internal sliding raceways.
One free wheel is intended to transmit a one-way torque mechanically between two mechanical components through the use of the sliding raceways forming part of the said mechanical components and of the jamming cams. The associated bearings are intended to provide correct relative centering of the external and internal sliding raceways and withstand radial loads between the external and internal sliding raceways. The operating principle of an assembly of free wheels is known, particularly from French Patent 2,618,195 (SKF).
According to the definitions attributed in the field of the art in question, an actual free wheel includes a plurality of jamming cams evenly spaced in the circumferential direction and held in the form of a ring by means of an alveolate cage of annular overall shape. The cams are designed to interact with the external and internal sliding raceways so as to transmit a mechanical torque by jamming the said cams between the two sliding raceways when these are given a relative rotational movement in a given direction, and no longer to transmit a torque if the direction of relative rotation is reversed (making it act as a free wheel). The alveolate cage is also intended to receive one or more elastic members, for example in the form of an annular strip-shaped spring, which exert(s) on the jamming cams a return torque in the direction promoting their jamming between the external and internal sliding raceways.
The bearings are components of annular overall shape including a radial web in the overall shape of a washer equipped with two axial rims, an external rim and an internal rim, which are intended to bear respectively on the external and internal sliding raceways. Such types of free wheels are used, for example, in automatic gearbox mechanisms for vehicles.
In some applications, it may be necessary to use pairs of free wheels mounted in tandem, that is to say axially side by side, it being possible for the external sliding raceways or the internal sliding raceways to be machined in a common component or in two distinct components mounted axially adjacent to one another. The use of an assembly with two free wheels in tandem, axially side by side, may be justified by the need to allow a high torque to pass, whilst using free wheels of "standard" dimensions; in other words, when the mechanical torque to be transmitted exceeds the mechanical transmission capacity of a single free wheel of so-called standard dimension, two free wheels of standard dimensions are assembled in tandem instead of using one free wheel with very wide jamming cams, the manufacture of which is a special order, and costly. It may also be necessary to use such tandem assemblies of free wheels when it is desired to transmit to one and the same member, mechanical torques coming from two neighbouring, but distinct, coaxial mechanical components.
To date, the assembly, in tandem, of free wheels comes from a simple axial association of two free wheels, each one equipped with two lateral bearings. The axial positioning of the lateral bearings of each free wheel is provided by means of a radial shoulder formed in the mechanical components including the sliding raceways and by means of added circlips held in annular grooves machined in the said components.
Such a conventional assembly of free wheels in tandem certainly gives entire satisfaction from the mechanical point of view, but it exhibits certain drawbacks owing to the relatively large number of assembled elements, which implies high manufacturing costs for the assembly, difficulties in handling the elements and in assembling them, and a large axial size of the tandem assembly.